package com.sloera.nio;


import org.junit.Test;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Date;
import java.util.Iterator;
import java.util.Scanner;

/**
 * 1. 通道(Channel)：负责连接
 * java.nio.channels.Channel接口：
 * --SelectableChannel
 * --SocketChannel
 * --ServerSocketChannel
 * --DatagramChannel
 * <p>
 * --Pipe.SinkChannel
 * --Pipe.SourceChannel
 * <p>
 * 2. 缓冲区(Buffer)：负责数据的存取
 * 3. 选择器(Selector)：是SelectableChannel的多路复用器。用于监控SelectableChannel的IO状况
 *
 * @author sloera
 * @create 2020/5/7
 */
public class TestNoBlockingNIO {

    @Test
    public void client() throws IOException {
        //1. 获取通道
        SocketChannel socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 9898));
        //2. 切换非阻塞模式
        socketChannel.configureBlocking(false);
        //3. 分配指定大小的缓冲区
        ByteBuffer buffer = ByteBuffer.allocate(1024);
        //4. 发送给服务端
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            String string = scanner.next();
            buffer.put((new Date().toString() + "\t" + string).getBytes());
            buffer.flip();
            socketChannel.write(buffer);
            buffer.clear();
        }
        //5. 关闭通道
        socketChannel.close();
    }

    //服务端
    @Test
    public void server() throws IOException {
        //1. 获取通道
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        //2. 切换非阻塞模式
        serverSocketChannel.configureBlocking(false);
        //3. 绑定连接
        serverSocketChannel.bind(new InetSocketAddress(9898));
        //4. 获取选择器
        Selector selector = Selector.open();
        //5. 将通道注册到选择器上，并且指定 监听事件
        serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
        //6. 轮询式获取选择器上的已经“准备”就绪的事件
        while (selector.select() > 0) {
            //7. 获取当前选择器所有注册的“选择键(已就绪的监听事件)”
            Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
            while (iterator.hasNext()) {
                //8. 获取准备“就绪”的事件
                SelectionKey selectionKey = iterator.next();
                //9. 判断是什么事件准备就绪
                if (selectionKey.isAcceptable()) {
                    //10. 若“接收就绪”获取客户端连接
                    SocketChannel socketChannel = serverSocketChannel.accept();
                    //11. 切换非阻塞模式
                    socketChannel.configureBlocking(false);
                    //12. 将该通道注册到选择器上
                    socketChannel.register(selector, SelectionKey.OP_READ);
                } else if (selectionKey.isReadable()) {
                    //13. 获取当前选择器上“读就绪”状态的通道
                    SocketChannel socketChannel = (SocketChannel) selectionKey.channel();
                    //14. 读取数据
                    ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
                    int len = 0;
                    while ((len = socketChannel.read(byteBuffer)) > 0) {
                        byteBuffer.flip();
                        System.out.println(new String(byteBuffer.array(), 0, len));
                        byteBuffer.clear();
                    }
                }
            }
            //15. 取消选择键 SelectionKey
            iterator.remove();

        }


    }
}
